I've seen this phenomenon but it's almost always at lower levels like high school or junior college. I think the primary reason is that the best talent in the U.S. often gravitates to the more glamorous sports. As a result, lesser talented athletes can train perfectly but only close the gap on their more talented but less well trained counterparts who have been doing other sports. At higher levels of the sport (good D1 collegiate athletics, national and international class) you'd almost never find a non-track athlete beat a track athlete.
ELITETRACK Founder